1. Field of the Invention
This invention relates to a contactless IC (integrated circuit) card communication system. This invention also relates to a method of contactless communications between a reader/writer and IC cards.
2. Description of the Related Art
In a prior-art contact IC card communication system, IC cards communicate with readers/writers when being inserted thereinto. In each of the readers/writers, the type of an IC card placed thereinto is detected as follows. When the IC card is reset, for example, when the IC card is subjected to a power-on resetting process, the IC card transmits a reset notice to a reader/writer. The reset notice contains information of the type of the IC card. The reader/writer detects the type of the IC card in response to the reset notice transmitted from the IC card.
In an example of proposed contactless IC card communication systems, readers/writers are provided on telephone sets (or automatic vending machines) respectively, and prepaid cards for using them are composed of IC cards which can communicate with the readers/writers by radio. In such a contactless IC card communication system, there is a chance that reset notices transmitted from different IC cards toward a common reader/writer collide with each other. A typical communication anti-collision technique is designed as follows. Every IC card is inhibited from transmitting a reset notice without receiving permission. Different IC cards are permitted to transmit reset notices at different timings.
Communication anti-collision techniques are of plural types. It is difficult to avoid a communication collision between IC cards designed according to different anti-collision techniques respectively.
It is a first object of this invention to provide a contactless IC card communication system which can avoid a communication collision between IC cards designed according to different anti-collision techniques respectively.
It is a second object of this invention to provide a method of contactless IC card communications which can avoid a communication collision between IC cards designed according to different anti-collision techniques respectively.
A first aspect of this invention provides a contactless IC card communication system comprising a reader/writer (RW) and IC cards which communicate with each other on a contactless basis according to anti-collision techniques; first means (200, 20, 30, 40) provided in the reader/writer for implementing identification requirement with respect to given anti-collision techniques among the anti-collision techniques; second means (320, 90, 60, 110) provided in respective IC cards among the IC cards which use different anti-collision techniques respectively for implementing answers to the anti-collision technique identification requirement by the first means at different timings respectively; third means (250, 20, 30, 40) provided in the reader/writer for requiring identifications of types of the IC cards in dependence upon the given anti-collision techniques in response to the answers by the second means; fourth means (350, 60, 90, 110) provided in respective IC cards among the IC cards which use different anti-collision techniques respectively for returning identification data of the related IC cards in response to the card type identification requirements by the third means; and fifth means (250, 20, 30, 40) provided in the reader/writer for identifying the types of the IC cards in response to the identification data returned by the fourth means.
A second aspect of this invention provides a contactless IC card communication method in which a reader/writer (RW) and IC cards communicate with each other on a contactless basis according to anti-collision techniques. The method comprises the steps of causing the reader/writer to implement identification requirement with respect to given anti-collision techniques among the anti-collision techniques by the reader/writer; implementing answers to the anti-collision technique identification requirement by the reader/writer at different timings respectively for respective IC cards among the IC cards which use different anti-collision techniques respectively; causing the reader/writer to require identifications of types of the IC cards in dependence upon the given anti-collision techniques in response to the answers for the respective IC cards; returning identification data of the IC cards in response to the card type identification requirements by the reader/writer for respective IC cards among the IC cards which use different anti-collision techniques respectively; and causing the reader/writer to identify the types of the IC cards in response to the identification data of the respective IC cards.
A third aspect of this invention provides a contactless IC card communication system comprising a reader/writer; a first IC card using a first anti-collision technique; a second IC card using a second anti-collision technique different from the first anti-collision technique; first means provided in the reader/writer for transmitting a first requirement signal to the first IC card and the second IC card; second means provided in the first IC card for generating a first answer signal in response to the first requirement signal transmitted from the reader/writer, and for returning the first answer signal to the reader/writer at a first timing, the first answer signal representing the anti-collision technique used by the first IC card; third means provided in the second IC card for generating a second answer signal in response to the first requirement signal transmitted from the reader/writer, and for returning the second answer signal to the reader/writer at a second timing different from the first timing, the second answer signal representing the anti-collision technique used by the second IC card; fourth means provided in the reader/writer for generating a second requirement signal in response to the first answer signal transmitted from the first IC card, and for transmitting the second requirement signal to the first IC card at a third timing determined by the anti-collision technique represented by the first answer signal; and fifth means provided in the reader/writer for generating a third requirement signal in response to the second answer signal transmitted from the second IC card, and for transmitting the third requirement signal to the second IC card at a fourth timing different from the third timing and determined by the anti-collision technique represented by the second answer signal.
A fourth aspect of this invention is based on the third aspect thereof, and provides a contactless IC card communication system further comprising sixth means provided in the first IC card for generating a third answer signal and returning the third answer signal to the reader/writer in response to the second requirement signal transmitted from the reader/writer, the third answer signal representing identification information of the first IC card; seventh means provided in the second IC card for generating a fourth answer signal and returning the fourth answer signal to the reader/writer in response to the third requirement signal transmitted from the reader/writer, the fourth answer signal representing identification information of the second IC card; eighth means provided in the reader/writer for recovering the identification information of the first IC card from the third answer signal transmitted therefrom, and for storing the recovered identification information of the first IC card; and ninth means provided in the reader/writer for recovering the identification information of the second IC card from the fourth answer signal transmitted therefrom, and for storing the recovered identification information of the second IC card.